upset tummy, back pain and grape sized lump

Day 1 of my period is on 30 June 2010 and my clearblue fertility monitor indicates that the follows:-

9/7 Low fertility
10/7 High fertility
11/7 Peak fertility -BD
12/7 Peak fertility -BD
13/7 High fertility
14/7 Low fertility -BD

Since 16/7 until today, I have abnormal upset tummy and back pain. I also have a grape sized lump on the right of my pantyline when i press it, it hurts a little and make me feel like going to the toilet. The lump appears and disappear, appear again and disappear again.

What happened to my body?