If it were mine I'd treat in hospital tank (hitching and heavy open ended air line aeration) with Furan II and Tri-sulpha. It's important too to drop the temperature to 68°F or as close as possible to inhibit the bacterial growth.
However, as you mention a bloated abdomen that is NOT pouch related, you may also have to treat with Acetazolamide (Diamox) as well. Treat for the full duration recommended and you probably will have to repeat the treatment as it takes time to really get the healing underway so you can see a difference. I've done up to 3 full treatments to get results.
Now, the really unfortunate part is that you MUST rectify the cause of this which is water quality conditions.
The water quality has deteriorated to the point the nasty bacteria have expanded to plaque proportions causing those visible wounds and possibly organ failure as well. THERE ARE NO TEST KITS available to the hobbyist to tell you when the water has degraded to this point so pro-active husbandry and water changes are needed, not re-active after the fact.
You can have all the normal test kits showing OK but none of those are going to show you the problem.
If there isn't sufficient husbandry/water changes for that particular system and tank loading, the degradation eventually shows up with these problems and it can take anywhere from months to even a year or so.
You might not be cleaning out the mechanical filters often enough (for me twice a week) and/or not removing trapped detritus and uneaten food (usually out of sight) combined with insufficient volume of water changes and frequency.
A highly overrated protein skimmer will help tremendously. (rated for AT LEAST 3X your volume)
Now as I see this as bacterial, General Cure and Praziquantel are for parasitic problems and not going to help at this time.
While aiptasia stings can cause wounds that get infected by bacteria, the location on your seahorse to me indicates those spots aren't likely to have been aiptasia related. More likely aiptasa stings show on the tail as it drags across them.