Underarm lumps. It much. please help.

Since last Saturday I had been having pain in my right underarm. This Monday after bathing when I took a quick look at it, I discovered that there is a big lump. I have had a few lumps in the past which were basically not so painful and big as the current one. I cleaned it and applied some talcum powder as I did earlier. But to my surprise, the greater lump is developing more smaller lumps which are turning yellow by the day and the pain is also spreading down the muscle associated with the arm. There is restricted movement of the right arm and I cannot sleep turning towards the right. This is a fright for me as I do not know what to do. The previous lumps that I had had healed by itself and I did not have to care about it much. Please help.