2nd oncologist appointment

I saw my oncologist on Tuesday, she really is such a lovely young lady. She’s arranging a PET scan to see if the tumours have responded and to check for spread. The results will determine whether I need 4 or 6 chemotherapy’s before surgery. She has given me some Loperamide to help with the diarrhoea too, I was concerned because I don’t want to become constipated but she explained if I only take it when needed that shouldn’t happen, her concern was I was going far to much and at risk of losing weight, dehydration or losing electrolytes. 
on Wednesday I received a call to go for my PET scan today (Thursday) I hope I don’t have to long to wait to get the results.