Hammer (my favorite fish) is getting over Fin Rot which he recovered from quite well. But today when he was swimming by the glass I noticed his belly has red spots on it. They are kind of in a triangle shaped patch on his lower belly. I'm so scared- I've never seen this before or heard of it. Does anyone have ideas what it is?

Have you checked ammonia levels? Maybe these are burns? Are they raised lumps or just spots? Is he still eating/active? The first thing I would do is a water change and see how it goes.

I'll test the water tomorrow- I gave him some melafix earlier and I'm letting him sleep now (it's 11:12 pm here). I just did a water change today and it's then that I noticed it. They almost look like they are internal- it's hard to tell because he moves so much and they are on the lower part of his belly. They are small red dots it doesn't look good at all. I wish I could draw a picture- it looks inflamed or something to me. Like I said it kind of looks like they are internal and I can see them through his "skin" but that could be totally wrong. Luckily he's still active and has an appetite but I am sooo worried.

Hammer was awake when I went downstairs so I ran water tests. Here's the info from the red box.
Keep in mind I changed the water a few hours ago. 45% water change.
Ammonia: .25, usually it's 0. The tap has an ammonia of 1 do you think that is causing the.25 since I just changed the water? I use Aquasafe water conditioner.
Nitrite: 0
Nitrate: between 5 and 10
pH level: 7.8
Tank size: This is a hospital tank he was in when he developed this (he was in it for fin rot) and it is a ten gallon aquarium. He's been in it two weeks.
Kind of filtration: it's a Whisper power filter for 10-20 gallons with just a plain filter cartridge in it (without carbon because the tank was medicated). There is an established bio-filter in the tank. The tank was fully cycled when I put Hammer in. I was keeping it cycled in hopes of puttin something in it.
How often do you change the water and how much: I usually change it on the dot every week, a 25% change- more if the nitrates are high. But July 4 was the last time I changed this tank. I should have been more diligant considering Hammer was recovering. He was recovering very well though and I was so busy I kept forgetting.
What kind of additives/water conditioners: Aquasafe conditioner, there was a finrot medication in the water- I never put carbon in the tank to take it out and I never did another water change after the last dose so maybe it's still in the water. I hope not. I just added melafix this evening to heal up the last of the fin damage and also because Hammer has some veininess in part of his tail.
How many fish in tank/what size: it is only Hammer in this 10 gallon tank.
What do you feed your fish: Bio-Blend sinking goldfish pellets, Hikari bloodworms, occasionally Hikari Daphnia.
Any unusual findings: The red dots on his lower abdomen and some slight veins on parts of his tail.
Any unusual behavior: He sleeps more than he used to but when he wakes up he is active and begs like normal and he's eating well. Dorsal fin is erect.
Chloramine level in tap: Don't know, but Aquasafe removes chlorine and chloramine.
If you have any ideas please let me know. I just feel terrible knowing I probably did this to him.

I do hope you'll be able to confirm what are the source of the dots (bite marks of somesort perhaps?). But since you mentioned a mystery ammonia increase, perhaps that's the cause. Give it time if the fish is not behaving unusually? My pearlscale actually has visible veins and red dots around her belly area (which is whiter than her general gold colouring), but it has always been there since I've got her (kind of looked like a cholesterol problem for a round fish like her). My other fish dekker (white fish) had small red streaks on his tail, but otherwise behaves normally. This red streak has been there for months now, but only recently the red colour started fading a bit (despite water params being normal). I do think a higher water aeration might have helped too (dekker's streak). Good luck!

Thanks- the streaks seem better today but I'm not sure about the dots. I could see them better today and it looked like a couple were on the outside of his skin instead of the inside. So maybe it's external. I guess if no one knows what it is I'll just assume it''s not harmful. I'm just afraid it's contagious but I'd like to get him in the main tank with his tank mates.

Well the red streaks are totally gone now and I got a good look at his stomach. It now looks like one or two red dots on the outside of his belly and the rest of what I was seeing I guess was just his stomach (he has a white belly). So I think it'll be ok. It doesn't seem to be getting worse. I guess it's just one of those things. I wouldn't post about it so much except that I love him so much and I worry about him. I know you all understand.