Your pharmacist is wrong.
Regarding turmeric - keep in mind that the active ingredient in turmeric is Curcumin. And curcumin makes up only about 3% of the turmeric root. So taking turmeric alone may not give much Curcumin benefit. A half teaspoon of turmeric has about 100 mg of Curcumin. Very small. The turmeric root has lots of nutritional benefits just like ginger root, and beets, and other roots, but when it comes to Curcumin, best to take a supplement that is all Curcumin. Look up C3 complex curcumin with bioperine. Bioperine helps with absorption.
Imatinib should be taken with food to avoid nausea. Taking imatinib along with your Curcumin will not make any difference. I did it for a year or so before switching to dasatnib. Selenium should also be taken with food - but like you are doing, alternate between a supplement or brazil nuts. Never take selenium supplement with brazil nuts at the same time. Too much selenium can be toxic. I alternate so I get both organic and inorganic forms of selenium.