Brief answer....explained below
Detailed answer....
Hello,
Thanks for the query.
I have read your query and understand your concern.
Risk of getting STD's are much less with oral sex as compared to vaginal or anal sex.
Out of these risk for HIV is very very low as compared to STD's like herpes,syphilis,gonorrhoea,chlamydia etc.
It is good that both of you have been cleared of STD's.
As far as sebaceous cyst is concerned,it is no issue at all as this is a cyst which arises from sebaceous glands and which doesn't possess any threat of any infection.
I hope it helps,however you are most welcome to revert to me for any further query.
Best of luck
Thanks

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