Add 1 Tbsp per gallon of Epsom Salt to some aged, temperature-adjusted (same temperature as the water the betta is already in) water.
Pour Epsom Salt solution into a containter.
Place the Betta in the Epsom Salt bath for 15-20 minutes. While the Betta is having a bath, change the water in his tank so that he has nice, clean water to go back to afterwards. Make SURE that the water in all of these containers is the same temperature, we don't need the Betta getting another disease right now.
Hopefully the Epsom Salt bath will help to loosen the blockage, just sit back and watch. The Epsom Salt bath can be repeated up to two times a day - just be aware that it is stressful to the fish, so if you can get him to eat the pea, give the pea a shot first.