Hi,I'm sorry you are having a hard time.I don't think it's having sex that is giving you acne though.
Cysts can be hormonal in women,and I would bet coming off the pill has alot to do with it.A lot of women go on the pill to stabilize hormones and get rid of acne.
Maybe your body is just readjusting to not having the pill, and once it is done your cysts will stop coming.It can take MONTHS for hormones to stabilize. Or,you could always try going back on the pill and see what happens.
If you don't want to go back on it and keep getting the cysts,perhaps a dermatologist could help you.