Possible placenta previa?

I just posted a question a couple of days ago....but I have some more questions. My next sonogram isn't scheduled until the 10th of April....and I don't want to be seem before then...(too many visits...) um....I did mention something about mucous with some blood....and just recently I've been having a lot of pressure in my pelvic area....and it hurts when I have ...I know that personal....but I'm just curious....every so often (throughout the day) I get sharp pains in my abdomine.....I was wondering if anybody knows what may be wrong? If it could be placenta previa? The only reason I thought about it possibly being placenta previa is because a nurse mentioned something about it when I called the hospital about the mucous....I have had a previous c-section before...and that does pose a risk for a possible placenta previa in a later pregnancy. Please if you have any information...I would really appreciate your comments/ advice