My Mother-in-law Has Acute Myeloid Leukemia. Her Platelets Are Very

My mother-in-law has acute myeloid leukemia. Her platelets are very low, 12-13, and she has recently experienced swelling and pain in her ankles. After looking it up, there is a name for this called thrombocytopenia, which is a side effect from low platelets. She told me that she put topical Lidoderm on the affected area, and it feels better. Is this ok, or could this cause more problems with bleeding and the platelets?