I am 19 years old and normal weight. I train everyday and live a healthy life style.
One week ago I was diagnosed with Yeast infection and for one week I have been taking medication.
It seemed like it was getting better, so yesterday I had sex with my boyfriend. While lying on my back there was an uncomfortable pain in the lower left side of my abdominal.
After a couple of minutes in a different position I was having a really bad pain in my lower pelvic region and it was so bad we had to stop. The pain continued for maybe 15 minutes. I also felt quite nauseous.
This morning I also had a little bit of pain in the same area, but it feels like the pain is more inside. I went snowboarding and also felt a bit of pain if the board was shattering and it made my body jump a bit up and down.
I have never had such a pain like the last one during and after sex before.
Appreciate quick replies.

Also forgot to add that my breast feel very sore and it hurts a bit if they are squeezed.

You should see your doctor/obygyn.

Could be a number of things and we can't really tell what they are based upone what you have posted. Sex is off the list for now until you get this sorted.