Hi lybrate-user, If your menses are irregular then first up you need to check with your Gyanecologist about the reasons behind it. There are many listed conditions ranging from infection
to endocrinal abnormalities causing irregular menses. A thorough examination of your vaginal orifice will help your Gyanecologist in understanding the reasons behind it. Doing sex with multiple partners if unprotected puts you into risk of transmitting STIs
. However even if you are doing sex with condoms there is still chance of some other infections to be transmitted. For more details do consult me online.