Pain down there from fingering

Hey guys! So my boyfriend and I are waiting to have sex but he does finger me. Kinda TMI, but like 4 months ago, he was able to put 4 fingers inside and I would be fine, it felt great lol. 4 was the max tho, and I was comfortable, a little sore the next day but not bad. When we hung out in September though, he fingered me like usual with only 2 fingers and after I felt a lot of pain. I told him I was fine, I thought I would be, but just below the entrance of my vag stung and I was super red and swollen. It almost looked like the skin above the hole that is naturally split tore a little. I was in pain for a good week and a half maybe, even water or Honey Pot soap was uncomfortable. We waited awhile and then tried again but only one finger and it definitely wasn't as bad, but I was still in pain a couple days after. We did it again a few days ago and no stinging! But I was swollen and for sure sore down there when I wipe and stuff. Any tips or ideas of what happened the first time?? This never used to happen! I had no issues after but I haven't been the same since September. Although he tells me not to feel this way, I always feel guilty when he does stuff for me sexually so I have been doing it myself through clit stimulation. I may do it too much, so I thought maybe that is making me less wet when he and I are together so it is not as easy. I am doing it more than I used to. Please give me advice this is really stressing me out! I can't talk to my parents about it.