morning sickness

Okay moms, so this is my second pregnancy after miscarrying my first. I'm at 11 1/2 weeks and I cannot shake this morning sickness! I've found that I especially get nauseous after taking my prenatals and iron supplements. Is there any advice you can give me to try to curve the nausea? My doctor prescribed me nausea medicine and it worked at first but now it does nothing at all! Helpppp!!!