I found it took well over 12 months to feel OK again after DS1 (tear, not episiotomy) - I think the lack of oestrogen due to BFing doesn't help, plus my MW said that there is a lot of soft tissue damage and swelling that takes a lot longer to resolve than you'd think. I was just starting to think about getting it checked out again when DS1 was about 15-16 months old, and then it suddenly got better. I think it might have been because my cycle was about to return (was still BFing and then fell pregnant straight away).
After DS2, when I had a ventouse and episiotomy delivery - everything was completely fine within a month or so. Which is why I really think it's a lot to do with soft tissue damage after the first vaginal delivery.
Lots of pelvic floor exercises helps with the ache.
Good luck, I hope it resolves for you soon, I know how depressing it is to still be carrying pain when your baby is months old!