Hey is it ok if I take the off brand of NyQuil and Benadryl (diphenhydramine) so I can fall asleep?

Not a great. combination for sleep. Combining two antihistamines benadryl (diphenhydramine) and doxalamine as well as a cough medicine is not a good idea. You could just use benadryl (diphenhydramine) which is diphenhydamine to sleep. It is the active ingrediant in most OTC sleep medications. Or better yet try some melatonin.