Swim bladder problem in paradise fish?

Overfeeding can cause this. It's common in goldfish who will take food from the top of the water and gulp air at the same time. They'll take in too many flakes which will expand and this causes the fish to flop around and be unsteady. The solution is to feed less, soak the flake first. Overfeeding can also cause constipation. Try feeding 1 pea, skinned. Epsom salt is also good for constipation. You'll have to look up dosage though as I don't know.

You don't mention your water parameters. Water quality can also cause this. Doing a 50% water change might help.

From what I understand and for others reading pls. correct me if I'm wrong but paradise fish, bettas and gouramis shouldn't be put together. They get territorial. I'd isolate the paradise fish until he's well and put the gouramis or paradise in separate tanks later. Stress causes many problems in fish - sometimes to the point of death.

Swim bladder disease is caused by bacteria. I don't think this is the problem here since it's been 10 days and the fish is still eating. I'd try the above suggestions first and then treat for a bacterial (internal) infection last.

By isolate I mean put it into another tank. Size doesn't matter as long as the fish can move around. You need to keep the water clean and add an airstone. If you can, add a heater so the temp remains constant. Feed the pea and take him off of his food for a couple of days. I usually float some plants in an isolation tank to help the fish feel more secure as netting and moving is stressful in itself. You're isolating the fish to get it away from the gouramis so keep that in mind when you go to put him back in his tank.

good luck