From my experience, and I'm just a couple of weeks ahead of you, I would suspect you're hitting a detox wall. I had considered getting 36mg nic a week or so ago to get me through the times that were bugging me. Instead I referred back to a vaping style that I had read about where you don't inhale the vapor, but rather hold it in your mouth for several seconds and exhale through your nose. The membranes of the mouth and nose absorb the nic more readily than the lungs. This gave me the added nic hit without upping my juice as well as giving my lungs a break from vaping too much in the attempt to get satisfaction. I'm glad I didn't order higher nic juice because once I got pass a few days of hitting this detox wall, I found that I'm actually ready to start slowing cutting my nic back.
Hang in there. Experiment with different ideas and suggestions to make the whole vaping experience enjoyable, and you'll get past "this" wall! I'm not sure if there's another in my path or not, but if there is, I'm convinced that I'll get past it with the help of this community.
Best wishes!