Naps? Anyone else have this problem

Megan • Mother to a beautiful little girl and expecting my second!
Every single time I've fallen asleep for a nap I wake up feeling extremely ill. I'm 18 weeks now. It's so bad I prefer to avoid napping altogether because I feel ill all the way to bed time. 
I've experimented with eating before my nap, not eating or leaving 1-2hours after eating before I nap but it doesn't seem to make any difference. I'm on dicletin and that doesn't help either. 
Anyone else have this issue or a theory as to what make be the cause? I'm going to bring it up with my midwife at this weeks appointment.