If I go to the doctor can they tell I have been smoking weed from a blood test?

no. they absolutly cannot do that. if you go to the doctor (for example) and they ask you if youve done any drugs even bad drugs like meth. u should always admit to it. when i used to smoke pot and i would have to go to the doctor i would always tell them that i smoke weed. they would lose there license if they told anyone you used any kind of drugs. when they take your blood they wont be testing for drugs. so i doubt they will see that you smoked weed. but if they did they cant do anything about it. the only way they could do anything about you using drugs is if your pregnant. then you would be harming someone else.