First thing I notice is you're overfeeding him. He should be getting between 3-4 a day, with one fast day a week. Also that's a wheat based pellet. They used to be really good but they changed their formula and now they tend to cause internal issues. I would try to find Omega One (feed same rate) or NLS Betta and you can feed like 5-8 of those. When was the last time he pooped and what did it look like?
Your fish is clamped, which is a sign of stress. Either there's a problem with the water or he's sick.. I do see a little fin rot.
In a tank that size he should be getting 50% weekly.. there's probably a big problem with water quality. You need to get your water tested. Do you have a drops kit for ammonia nitrite and nitrate? I imagine at this point you will need to do a series of several 25-50% water changes over the next week to get things up to par.
If you're looking for a different conditioner Prime and NovAqua Plus are the only ones that might help with ammonia/broken cycle water problems.
Adding more conditioner won't help. It would be a good idea to quarantine him if you can keep him warm, but if you can't then I wouldn't move him. I also wouldn't use bettafix. If there are no live plants, I would treat with aquarium salt at 1 tsp per gallon. I'd also give him a couple days without food and monitor his poop during that time. You may need to switch to epsom salts but the aq would be good for the fin rot.