Hi,
by swollen underarm did you mean a swelling in the axilla.
There are numerous causes for this depending on age factors.
In the middle aged and elderly it could be considered as an secondaries in the lymph nodes from the breast.
In the young females it could be an accessory breast tissue, or an infectious nodes.
Hi,
Do you have a lump on palpation or breast self examination? It could be due to tight clothig or trauma or due to an infective process like mastitis or cystic lesion of the breast or related to your menstrual periods - due to the hormonal fluctuations that occur at that time. You need a clinical evaluation and need to see your physician at the earliest.Get a screening mammogram done and ask your physician if he thinks you should get a USG done too. It could also be swelling and inflammation of the lymph nodes in the region and therefore needs to be investigated further. Till you get an appointment try to wear lose clothing and apply some soothing lotion. Also take some OTC antacids for the gastroesophageal reflux or some drugs to improve the gastric motility and this should help improve your digestion also.Take some antispasmodic medication for the PMS, it should definitely help.