Could I be pregnant?

Five weeks ago I had sex with just spermicide as protection. These past 4 or 5 days I've started to get extreme nausea all day but especially when I wake up, my breasts hurt, I'm eating everything in sight, then puking it up, I've been getting this almost cramp like feeling in my uterus, I've been very gassy and my period only lasted 3 days when it normally lasts 5-6 days. What are the chances??