Healed lip piercing swollen after changing jewelry

I have snake bites but why does only the right side gets swollen and irritated when changing jewelry? I switched from the original studs to horseshoes yesterday after 3 years so they're definitely fully healed. If it can help I noticed the thickness of my lips is uneven (problematic side slightly thicker, therefore jewelry is more snug, but unless swollen not uncomfortably so)

Should I switch back to studs or keep them for a bit and see if it adjusts?