Hello. I had the Nexplanon implant put into my arm in February and my boyfriend and I started having unprotected sex about 2 and 1/2 weeks ago and I just started having pregnancy symptoms last week... Stomach pain, headaches, diarrhea, nausea, very bloated, and mood swings. These are all the symptoms I had with my son who is now a year. I know that those are common side effects, but I didn t start having them until last week. My period is also late this month...