Over the past week some sort of lumps are starting to develop on the side of his body.

Def not the best pic.. I will try to get some better pic later. but you can see there are 2 white spots with one in the middle sticking out a bit.
I noticed that he started to have a white spot (the one around his tail area in the pic) developing last week and I thought it's fungus. so I started dosing pimafix..
So initially it looked like a white circle with the middle unfilled. As the week past by I found the circle getting filled up.
So I thought it could be a wound that he had and it's healing... and it does seem to get a bit smaller.
Yesterday I found that he's having a second lump (the one in the middle area of the body in the pic). And today it has grown and starting to stick out.
I have stopped dosing pimafix when I thought he's recovering. I basically dosed for 3-4 days.
I will be doing a water change tomorrow.
PARAMs:
PH: 6
Nitrate: 5
Nitrite: 0
Ammonia: 0
water change once per 1 - 2 weeks @ 50%.
diet : mainly wriggler worms. sometimes raw shrimp.
tank: 25 gal
he's not new. I have had him for 3+ years.
His appetite seems to gone down. But he did ate for me. Just not as eager as he would usually.
Any idea what that lump can be? and what medication can I use to treat it? there seem to be a 3rd one coming out on the other side of his body. I am really worried.
Please help! Thanks in advance.