Hi, I am a fairly new homeschooler (we started last year after spring break). It took a while for us to eliminate the tempermental meltdowns. The doctor said my DS had post traumatic stress disorder. She said it was normal for children to have an emotional breakdown when they are removed from a stressful situation.
That definately made sense in our situation. While we were "recovering" from public school, I tried to be patient and I used a lot of alternative teaching methods, such as videos, songs in the car, field trips, etc. I could have skipped this and just hung out (which is sometimes the best thing!), but I was worried that I'd be shirking my teaching duties and I had a county review coming up soon.
After the summer, I was prepared to have similar issues with my son when school started. However, he hasn't had any of those problems this year so far. (Thank God!) I don't feel like I necessarily did anything special to get us here. I just think time served as a terrific healing agent.
I hope your little guy comes out of his funk soon. I read once that you should hug your child and tell them you love them 10 times a day...whether you feel like it or not. There have been times I have had to apply this rule to myself to make it through family challenges (we have 6). It's been as good for me as my children.
I should note that two of our children are ADHD (not our gifted child). Without their meds, they would be unable to learn. I see many unfocused behaviors in our gifted child as well. However, they do differ significantly. For example, DS7 can read for hours, draw for hours, etc. but sometimes tunes me out when I am covering material that he finds uninteresting, or he'll attend a sporting event and tune out the coach, because he really doesn't care about the activity. -- Also, when we started homeschooling last year, he would constantly yawn or fain indifference, because he had genuinely lost his love of learning.
On the other hand, our 2 with ADHD cannot get through a simple book, repeat questions over and over, because they cannot retain answers, spill constantly, misplace items on a routine basis, etc.
So, I guess I am trying to say that what appears to be ADHD may or may not be. It could be learned boredom/indifference, or it could actually be a brain/nerve disorder. I think a mother's intuition is good, so I would recommend you have him tested. However, keep in mind that (from what I've read), many gifted children gets placed in the same bucket because they are divergent thinkers.
Hang in there. Homeschooling is definately harder than I thought it would be (mostly because I want to do the best job possible). However, it is also incredibly rewarding once you get past the initial settling period.