1. going by the history, [line which stops in the mid line (center of torso] with pain should be suspected for Herpes Zoster
2. You should see a Dermatologist
, regarding skin symptoms [ for any vesicles over the skin] along with appropriate line of treatment [anti viral drugs like acyclovir
and pain killers like ibuprofen
and calamine lotion for soothing], and if he thinks there is secondary infection due to vesicles he may prescribe silver sulphadiazine or soframycin
3. since swelling and lump can be excluded by your history, still check with chest X -ray to rule out the possibility [if any], please seek medical assessment.