This is a 38-year-old female with a past medical history of cancer as well as migraine, who presents today for annual examination.
The who is unnecessary and would be considered a comma splice in this instance. Also, as well interrupts the flow of the sentence and could be replaced with and.
If these changes were made, the sentence would read the following:
This is a 38 year old female with a past medical history of cancer and migraine who presents today for annual examination.
I hope this helps. Feel free to contact me with any further questions.