Personally we had to stop the vaccinations for our daughter (she will be 3 this month) becasue it threw her into a tailspin- too high- then too low then too high- it would take weeks to get her back on track and even though they assured us it wasn't normal we saw when she was older she would regress with development (even if she was really sick and her numbers would be out) so the vaccinations just were not worth it for us.
Interestingly she did get chicken pox as she had not been vaccinated for it and she was very very sick for days and her phe levels did not fluctuate at ALL! So i was glad we opted out of that vaccine!
Apparently if you separate them and delay them it helps- we tried that first but didn't work for our family.
And stress- oh mamma there is stress- the first year is horrible – but the second year is better and now our daughter is stabilizing and we'll go months with no fluctuation in numbers and she is an amazing little girl and everything is great and i wonder why did we ever worry- then she'll get sick and i'll go crazy again. The joys!