I have a bruise on my arm thats growing, what could cause this? My liver is swollen.

Be seen. An expanding bruise is an expanding bleed under the skin. If your liver is not working properly to make blood coagulation proteins, it could be a sign of a more serious problem. You should see your doctor.
See doctor. A growing lesion on the skin may represent a skin lesion. Sometimes they can look like a bruise and be confused with one. Have it looked at soon.