Congratulations on your efforts to quit smoking! I so hope you're successful, as there are so many negative side effects to tobacco!
I've never smoked, but been around smokers all my life. Nicotine is a drug. Seems reasonable that it affects a body in a whole bunch of ways, and certainly could dampen symptoms that you're now experiencing. Given the huge negative effects of nicotine, though, I'd think it worth it to keep trying to stop. You might also be experiencing nicotine withdrawal; like withdrawal from other drugs, that's not a pleasant thing.
Hang in there. Ask your doctor if there are things you can do to minimize the withdrawal effects right now, so that you can be successful in quitting smoking. Good luck!
...I am not a doctor, nor health professional, and don't pretend to be one, here.....