Just some of my ideas: (hopefully someone else will be able to come in who is a real expert on BF etc.)
He may be still adjusting to having to relearn how to latch and suck after doing it a different way for 7 weeks and then getting his tongue tie snipped.
He may have had to try and suck quite hard to get milk out before his tongue tie was fixed and now when he puts in the same amount of effort into his sucking the milk comes too fast because he has the right latch now.
OR it might be the other way round in that it used to come quite fast but now when he tries to suck the same way as he used to - it doesn't work because his latch is not quite the same. So, the milk doesn't come as fast as he would like or was used to.
Your milk flow also may have to adjust to his different way of sucking.
Your milk supply will adjust soon hopefully.
If you think your milk is coming down too fast for him for the moment - try feeding with him in more of an upright position (this will help with the gas as well) and you could also try leaning back a bit more. I used to feed Jude with him pretty much in a sitting position beside me and me leaning as far back as I could - almost lying down! My supply settled down after a while