Hello. I was wondering if it’s safe for my 6 year old to take azithromycin, dimetapp night time, and children’s Tylenol together?

Probably safe but... Dimetapp or other over-the-counter cough-cold medications are not recommended for younger children nowadays. Such meds were used very often in the past. That said, using small amounts under the guidance of one's own pediatrician should be safe to do. Taking the 3 medications in the correct doses, for no longer than the number of days recommended by one's doctor, should be safe.