My 11 y.o. DS has ADHD. It was first pointed out to me, very gently, when he was 3 1/2. The teacher said, "We took the kids on a field trip, and it took 5 moms to keep one little boy from getting lost or hurting himself!" As a teacher myself, I know that teachers are not allowed to diagnose, only to suggest that you pursue testing. At first, I didn't want to hear it, and my pediatrician told me that the teachers were all wrong. After several more years of difficulties, I did have him tested, and sure enough, there was really no question about it. IMO, it's worthwhile to find out, if the issue is ever raised. More info about your kid never hurts. But go to someone really well qualified. Sticking a little kid on meds without careful guidance is not good doctoring or good parenting.
For us, a combination of meds, carefully supervised by a topnotch psychopharmacologist, regular meetings with a psychologist, social skills classes, neurofeedback, some hypnosis, and CONSTANT work on structure have all been helpful. One of the most vital things I spend my mom time doing is talking regularly to his teachers, to give them ways to help handle his weaknesses, and to hear how things are going. I've learned from some bad experiences over the years that teachers only get as difficult as the op described when they're totally frustrated and feel helpless. I do a lot to minimize frustration and helplessness on their part by letting them know what has worked, and making it clear that I'm willing to listen to them. It's all incredibly time-consuming. My house is a mess, my yard is a joke -- but my kids are growing up stronger and better each year!
Linda -- proud mom of Rachel (20), Joshua (15), Elisheva (7), and Moshe (3), and 2 wonderful grown stepdaughters.