High platelets

A couple of weeks ago, Braylee was running an off and on fever for a few days so we finally brought her in to urgent care (fever started on Thurs, we brought her Monday night).  After an hour and a half (catheder atempt and x-ray), we left being told she likely had a viral infection and to just ride it out.  The following Thursday (so 1 week after the fever started), it was still the same so we brought her in to her pedi.  Pedi checked her ears, did a strep test, x-ray, and drew blood.  Before we left, she said it looked like Braylee had RSV but would wait to confirm until the blood tests returned.  Friday AM, doc called and said her platelets were high (660 - normal range is 140-440) which would indicate a bacterial infection and started her on antibiotics.  We went back this last Thursday for a follow up (fever never returned after antibiotics were started) where they did a blood test again.  Well, her platelet count came back even higher -- 877.  We'll be going back in a few weeks to do another blood test. Has anyone had any experience with this? I'm concerned because all of her other symptoms were gone, but her platelets still shot up after almost a week on meds.

My mom has thrombocythemia which causes high platelets, but it's not supposed to be hereditary.