Why Is It Swelling If Physical Therapy Is Done?

removal of all lymphod left arm, due to breast cancer 6 month ago.. how long will numbness and swell disapate... been going physial therpy trying to get full shoulder /arm motion, but seems to swell more when session is done. i've been using a tempoary arm compressor, i cant afford recomended ones, raising arm above shoulders. what else can i do to mimmimum swelling and gain my felling back? thanks Ceci