tightness under arm post mastectomy

sme

Am two weeks post mastectomy for invasive lobular carcinoma. Have PT appointment in 4 days but am looking for suggestions in the meantime. Had sentinal node biopsy along with mastectomy. Despite trying to keep the arm moving and trying to stretch it out, it seems to be getting tighter and definitely hurts more. Feels like a string is being stretched way too tight in my arm when I try to bend it straight and when I try to move it in certain directions. Otherwise I can use my arm okay. Have PT appt scheduled but need to try and work on it a little as it does hurt. Am trying to keep it elevated at times. Am taking ibuprofen. One source says use heat the other says use ice. Suggestions on what may have worked for others? Appreciate feedback.