First, I want to say I think it is very distasteful that someone would accuse you of putting your children at risk because you didn't vaccinate. It's a personal choice. I believe parents need to educate themselves on all aspects of their and their children's health care. Then, they can make educated decisions. The medical community, most of the time, tries to push a 'one size fits all' type of health care on us instead of looking at each individual case. The recommended vax schedule is very aggressive and the medical community refuses to recognize that it could compromise some small children.
There is no way to know if the hair loss is or is not caused by the vaccinations, a food allergy, or exposure to something else.
My sister has a friend, who when she was about 8, began loosing her hair. She too had very thick hair. Eventually she was diagnosed with allopecia. They don't know the cause and there wasn't any treatment. It was very hard for this young girl. Thankfully, she didn't loose ALL her hair. She was able to pull up her hair and wear it in a bun on top of her head to cover up the bald spots that eventually formed. The good news is, once she got through puberty, it seemed to reverse and now she is a young woman in her twenties with no hair issues.
I also have a friend of mine, who after the birth of her daughter lost her hair. At first the docs just thought it was the normal hair loss you experience after giving birth. But, she knew differently. She knew it was too much. She literally bagged the hair that she pulled out in one morning and took it to her next appointment. The doctor agreed it was too much and did some testing. They found she had a vitamin deficiency and her hormones were completely out of whack.
I would take your little one to the doctor and explain what is going on. Keep asking the questions and keep pushing them until they can give you an answer as to what is going on. We are the only advocates for our children!