Well its hard to get 20 pounds worth of coke. The bigger picture is the destructive behaviour that is the big sign. If you know what hes like and hes not right usually instinct is right. The behaviour gets worse trust me I know. I’ve found clarity and peace in myself as I’ve displayed patterns like this when I was caught in it.
If you are unsure test him.do not give him money regardless of the situation. Do not lend him your car do not enable him in any way.
If the test comes back positive then you have to create a plan what’s going to make you happy and what’s best moving forward.