I totally understand what you are going through. Panicking comes when you don't have answers. Getting the answers and the information is hard when you don't know where to go or who to ask or even how to tell your story!!
Having been through some of these issues with my 7 yr old, I can tell you, just start calling around and making appointments. Go to the library and check out books like _The Active Alert Child_ and books about sensory integration disorder (sometimes called SPD, sensory perception disorder) and everything in between that sounds like it *might* be him. You can't read too much!!
Get some testing done. Allergy testing (food and environmental allergies can cause hyperactivity, aggression, and attention problems in children.) We got blood testing, scratch tests and MSA testing (Meridian Stress Test) The latter was through Home First and was the most useful for us. Check out the Feingold Diet- removing preservatives, artificial flavors and colors from my daughter's diet made a tremendous difference in her ability to sit still. She's still the same quirky her, but better! We had heavy metal testing (urine porphorins), lead test w/blood test, hormone testing w/blood test, complete CBC panel, anything I could find online that *might* be the cause of things, we tested for!! I have a great ped, Dr James Sanders, in St Charles who did the testing for me.
We also did psychological testing with Dr. Michael Appleby in Hinsdale (though he has an office in Chicago as well) He is a pediatric neuro-psychologist. He tested for giftedness, delays, sensory disorders, etc etc. It took awhile to get an appt, but it was worth it. We also did EEGs to rule out anything like seizures. You *DEFINITELY* want to have an EEG before you medicate. Lots of the medications they use for children (Risperdal, Abilify, etc etc) can cause seizures if your child is predisposed. You can't know this without an EEG. Demand one!!!
Get second and third opinions on everything. Believe me. Don't totally rule out meds if that is what he NEEDS. I believe it is our job as parents to understand and give a child what they NEED. Medication might not be the answer (and for me it has to be absolute last resort!!) but it may be what has to happen for him to function. There are also homeopathic routes you can take, and if those don't work, then you can go to a compounding pharmacy (luckily we have a lot in our area) where they will make the medicine more "pure" for you without all the added things like flavors and colors, sugars, etc.
Also, I'd like to mention one last thing. 5 years old is just the age where you are seeing what kids are capable of. With my daughter, until she was 7, I kept saying, "But she's only a __ year old. That is how they are." You will, as he gets older, start to distinguish what is disobedience and what is truly out of his control. My daughter is diagnosed with Tourette's Plus. She had behavior and hyperactivity before she was diagnosed and probably would have been medicated for ADHD had I pursued it and allowed it. Tourette's (and some other things) often don't show up in their TRUE form until later, so you start with things like behavior problems. While sometimes you have to treat the symptoms, it's always best to investigate the root cause (which it sounds like you are trying to do.)
If you need help finding doctors or books, or online support groups, etc. OR you just want to talk it out, feel free to message me. Having a child who is "a handful" can take over your life and be exhausting and depressing. Hang in there. There are people out there who can help!!!
Hugs,
Amanda