My Daughter (22 Y.o) Started Having A Cyst On Her

My daughter (22 y.o) started having a cyst on her left neck in March 2015. We went to a EENT doctor and he aspirated the cyst for biopsy and had her for CT scan but results were all negative for bacteria. Doctors initially suspected branchial cleft cyst but since behavior and manifestations of fluid accumulation were not consistent with branchial cleft cyst, they started to look at t lymphatic malformation or chyle fistula (milky white /fatty fluid being drained from her inflammed tissues). They said it's a very rare case and they are still trying to figure out whats causing the leak or lymph node/vessel problem. My daughter goes to her doctor ( head, neck thoracci surgeon) like every two weeks to have the fluid drained. She also took 3 courses of clindamycin and recently penicillin. Just today she tested positive for TST but have not CXR results yet. Do you think she has A-typical mycobacteria? Did you have a similar case like my daughters? Pls adv. Thanks