EVEN IF YOUR ONCOLOGIST DID NOT MENTION THIS TO YOU, HE IS PROBABLY MORE CONCERNED ABOUT YOUR WEIGHT LOSS THAN THE OTHER. AND EVEN IF YOU TOLD HIM YOU HAVE BEEN TRYING TO LOSE WEIGHT, THEY STILL WORRY ABOUT WEIGHT LOSS.
ALP elevations can be related to various conditions such as liver disease, bone disease, hyperparathyroidism, and mono, and also can be associated with numerous medications. They don't tell a lot, unless correlated with other clinical findings.
I know that it is difficult not to worry about recurrence anytime something changes, but try not to "totally" freak yet.
I think your Dr.'s approach is reasonable, but if you are not comfortable with his recommendation, you might "negotiate" to repeat the test in 4-6 weeks rather than 3 months.
Please keep us posted on how you are doing.
Best wishes...