Hello & Welcome to Just Answer,
Having gone through your description, since we have a swollen and aching neck (in front), we have to discuss with our doctors about a condition called ‘thyroiditis’ which may also cause a decreased wbc count.
There could be other causes which I think that your doctors would be looking into, after a whole lot of probabilities have been excluded. This would include the following:
(a) Lupus and other autoimmune disorders
(b) Chronic viral infection/undiagnosed infection
(d) Rheumatoid Arthritis
(e) Some medicines that you might be taking or would have taken
(f) Bone marrow disorders/ leukemia/etc.
Having said that, we might be dealing with GER (gastroesophageal reflux) or GERD (gastroesophageal reflux disease) which could be causing for the problem that you have regarding burning feeling below the breast bone associated with uncomfortable feeling. Stress could also play a part in aggravating this problem, as well as in the low counts that we are having.
I hope that this information helps answer your query. Please feel free to inquire if you have any remaining concerns/ doubts, as it shall be a privilege and a pleasure to try and help as much as I can. Best wishes.