In theory, oral contact with menstrual blood might slightly raise the risk of HIV or hepatitis B transmission. But still the risk is too low to measure and to my knowledge no such cases have ever been documented. Your Crohn's disease and possibly weaked immune system don't increase the risk. My advice is to just put the entire event out of your mind. But if you are especially worried and need the reassurance of a negative HIV test result, get tested a few weeks after the event. Assuming you have no other HIV risks you don't mention, you can be 100% confident the result will be negative.
Good luck-- HHH, MD
Thank you Dr Handsfield for your reassurance. There were no other HIV risks that I am aware of. I will do, as suggested, and get tested as soon as feasible. Here, the clinics won't test you until 3 months after the suspected exposure so I shall wait until then.
Thank you once again.