The first time when you bled alot could have been that you would have 'broken cherry' As they say.. Now it could be that his nails are too long, or too rough? Oral sex you're fine though right

You may just need to use a little more lube (spit works too).
He could be doing it too hard or just his finger nails, but everything will probably go away if you do use lube. Does it hurt every time?
If everything else is normal then I don't think its an infection.
You may get more pleasure if he stimulates your clit, I know just being fingered doesn't really do much for me, maybe you're the same.