I Have Had The Implant Since Dec 2013, This Is

I have had the implant since Dec 2013, this is the second implant I have had and I'm experiencing it differently. I have had really sore breasts for about 5/6 days, they have got noticeably bigger and heavier. I have also had quite alot of white vaginal discharge, which I have never had before to this degree. I have a had a headache for 3 days. I'm tired all the time! I have back ache. Also I have just wanted to eat cheese for the past few days. Is there any chance I could be pregnant. I have had periods during the implant and i was due have one 25th of last month, I understand periods can change, or go away when you have the implant but i wad supposed to have one 3 weeks ago. Is it possible to conceive whilst having the implant in?