Help with diagnosing issue

I have a male Betta with something that I can’t diagnose and I was wondering if anyone here could help.
He has had a swollen side for a while I just assumed it was his stomach after eating but now it has started to get white bits on it and I’m not sure what it is. I have attached photos, they’re the best photos I can get of him as he is still very active and eats no problem. He swims around as if nothing is wrong with him.

I haven't seen that before. It could be two different issues (e.g. internal growth plus external fungus). How long has he had the white bits, are they flat, lumpy or fluffy?
Extra water changes won't hurt.

Naughts said:

I haven't seen that before. It could be two different issues (e.g. internal growth plus external fungus). How long has he had the white bits, are they flat, lumpy or fluffy?
Extra water changes won't hurt.

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He has only had the white bits for a couple of days. They don't appear to be fluffy, the just appear to be like white scales. I have treated his tank with interpet anti internal bacteria fish treatment so will see if that does anything. I have recently been having issues with my heater, it was overheating his tank to about 30°C. I have replaced his heater last night so hopefully this will make his conditions a little more stable. I'm thinking the white could maybe be a sign of stress caused by the temperature fluctuations. The lump in his side has been there for months but never white on it. He doesn't appear to be in any distress with it and is still eating as normal so that's a positive I suppose.
I do water changes every weekend but I could start doing a couple more if nothing else works.

I suspect either a tumour, or more likely, an incurable Mycobacteriosis infection. They can carry the latter for a long period, but as it grows, white scales are often a sign, especially if the lesion is squarish. It's bad news all around, I'm afraid.

I'm not too sure about the white bits but he is extremely thin. What and how much are you feeding him?

GaryE said:

I suspect either a tumour, or more likely, an incurable Mycobacteriosis infection. They can carry the latter for a long period, but as it grows, white scales are often a sign, especially if the lesion is squarish. It's bad news all around, I'm afraid.

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I thought possibly a tumour at first. He got worse throughout the week, the infected part seemed to get bigger and he was struggling to swim. Staying at the top and occasionally on his side, I thought I’d lost him a good few times
I’ve been treating him with interpet anti internal bacteria and after a week he seems to be swimming better and is looking a bit brighter. I’m hoping if I keep treating him with it maybe he will be ok but we will have to see.

Sully38 said:

I'm not too sure about the white bits but he is extremely thin. What and how much are you feeding him?

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He gets fed once a day with tetra Betta flakes 5 days a week, one day with either king British bloodworm treats or king British daphnia treats. I don’t feed him one day of the week.

This is him today, the white looks more prominent. I can’t tell if it’s his scales lifting off, some kind of abscess bursting or if it’s fungal. He is swimming a lot better than earlier in the week and is eating fine.