Smoking is really doing you no good. You are suffering from its negative effects now. Good thing that you're able to realize to stop it and do not ever go back with that bad habit again. Anyway, you said doctors doesn't see anything wrong but still you feel terrible, have you consider asking for a second opinion from other health professional? It's not bad at all to seek some health advice from other health expert.
My uncle had quit smoking completely without trying e-cigars or other smoking alternatives. He had developed anxiety, depression and some other nicotine withdrawal symptoms. For several years, he tried to avoid the desire and the irritability by doing stuff that could make him happy. When he was able to do physical exercises, he did it regularly. We also always talk to him so his attention is diverted from wanting to smoke a cigarette.
I smoked a pack or two a day for just over 42 years.I quit cold turkey.That's not saying I am any stronger than you.Because I am not.Give your self a break.You are far more stronger than you give your self credit for.Can you imagine what the inside of your lungs look like? I have cleaned very thin layers of that crap from windows,if you get my drift.Stop letting it depress you.It's a race you have already won.Please understand I am not trying to push any I did it you can too crap.We are two totally different people.I am just trying to help you see and use your inner strength.I do not know the reason you decided to quit,but I sure hope you did it for yourself,and nobody else.I quit smoking the day I went in to have ACDF surgery on my neck.That was on June 11th.I also think if you stop applying smoking to all of you symptoms and just let the memory of smoking go away,you will get better.Best Of Luck! Don't Start Smoking Again!