i dont use melafix, some have had overdoses and killed there betta using it. if dosed properly it should be fine. i find the things i suggest should fix most fin problems. if it dose get bad enough i have used maracyn with good results.
i wouldnt feed shrimp personally. bettas can get constipated easily and i think shrimp would be very hard on there digestion. the bettas have small bellies and will eat themselves to death.
the thera a is good stuff, i feed most all my fish the thera a. i actually feed my bettas the NLS betta formula and soak it but either should help.
8g Fluval 1M CT Betta
125g 5 Blood parrots, 1 Green Severum, 8 Dension Barbs, 10 Yoyo Loaches, 1 RTS
75g Angelfish, 3 EBGR, 4 Siames Alage Eaters, 12 Harlequin Rasboars, 1 BN Pleco, 1 Swordtail
33g long cherry shrimp, 8 pygmy corys, 5 ottos
15g 2 GBR