Have you ever talked to your doctor about this? The fact that you are swollen inside sounds like it is either he is pounding inside you too hard (and then he needs to lighten up/ change postions) or maybe an allergy to something you are using during sex.
Do you use condoms? - could you be allergic to latex? Have you tried different lubrications - could you be allergic to one of the ingredients in the lubrication? If you are using waterbased - try silcone and vice versa. If you are using flavored - try unflavored.
If none of the above - then you need to discuss this with your doctor.
Susan