I hear you. Took me 4 yrs to find a diagnosis from an ENT. Since then took low level antidepressants, gabapentin, steroid shots in the vagus nerve in my neck, nothing really helped. I have found an over the counter cough syrup with Elderberry called Zarbee's which helps the cough...I take mostly at night so I can sleep a little. For the phlegm attacks I don't have any suggestions, thankfully I don't have that symptom. Acupunture? I've tried a little and it gave me back some energy, but it's 6 hrs away and I only had 2 treatments. If you have a chinese doc close by, you might try that. I've kinda given up on regular docs!!
Good luck!