Issue of Blood 7 yr.old female

Hello- My 7 year old female rabbit has just recently had an issue of blood. The amount is equivalent to about 4 Tbsp. She is the most loving and patient bunny to my 10 year old daughter. since this issue of blood she is acting a little testy, but is retuning to normal behavior. she has never had any health problems at all, to you have any thoughts?
   
Thank you so much.