Is your fish a fantail?
Use pure bicarb soda (used for cooking) to up the PH, only need to add a little and it works really well. Remember to only add a tiny bit at a time (to avoid PH shock or overdosing) and keep testing to check if you have reached the desired PH level. Check nitrates are not above 35ppm, if they are do lots of water changes to bring it down. High nitrates often affect the PH.
Your fish seems to be suffering from something called Swim Bladder disease, I believe. A friend of mine has a fish with it but it's doing very well now. Here is a list of things that helped her fish...
1)Put a heater in and set it to 22c: this helps the fish to poop more, floating is often a sign they are blocked up! Fancy Goldfish can live happily at 22c but you will have to clean the filter more regularly, and make sure the tank is well aerated as warmer water has less oxygen. It would be better to get a heater which has a protective cover, such as a rena heater, as if the fish is floating by it the fish doesn't want to run the risk of getting brunt.
2)Cut feeding to every other day, you might be feeding too much or the fish maybe very greedy!
3)Dose with epsom salt (see you are doing that already)
4)Add GREENS to your fishies diet:
Cooked peas (squish the peas, feed the middles, and discards the shells)
Algae Wafers (to get the fish interested in them as food feed as the only food for a few days then mix with regular food twice a week).
Spirulina flakes (mix with reguar food ... can get these on ebay)
