Rash/Bruising at surgical site

My mom has been diagnosed with breast cancer stage 3 and had some lymph node tested positive and removed.  She has undergone her first treatment of chemo with a follow up shot to boost her white blood cells.  After the shot she developed a rash/bruising, it really looks more like a big giant bruise at the surgical site. There has been no fever. She hasn't been able to see a doctor (oncologist) because he's on vacation.  The nurse prescribed kaflex.  It's been three days and nothing has happened.  The coloring is mostly a maroon red with some yellowing.  I tried looking up info on the internet and saw some info on hematoma.  Could this be it, and could you give me some more info on it? If this isn't it any ideas on what it could be?  Her surgeon is also on vacation.  Thanks.

[Cleveland Clinic]

Dear Wendymlb:  Without evaluation, including physical examination, it is impossible to speculate on what this might be.  It is possible that this could be a hematoma (a bruise caused by bleeding under the skin).  If it is a hematoma, these can take a long time (months) to resolve.  However, if she has not been seen, she should be seen to determine what this is.  You should make an appointment for her to be seen by her surgeon or oncologist upon their return  or with a covering doctor.

[peekawho]

There is always someone covering when a doctor is on vacation.  The office will know who she can see, if she is concerned.