Ooof. You need to get on an appropriate birth-control pill, or to get an IUD. The day-after pill is not meant to be randomly used just whenever, it is not good for you. They call it "emergency contraception" because it's meant to be used only when there is an emergency, not all the time. Also, it would be a good idea to get checked for STDs.
Back to your question -- it doesn't sound like you're pregnant. But if you got pregnant from the guy on April 26, you would be totally aware of it by now, and your pregnancy tests would come up positive. So, you aren't pregnant from the April guy.
Yes, day-after pills can mess up your cycle. Also your body. So please get real and go to Planned Parenthood and get some birth control. Also, start using condoms (even if you are on birth control) so you won't be at risk for herpes, chlamydia, syphilis, gonorrhea, genital warts, vaginitis, viral hepatitis, and HIV.