sorry so are you saying you take 5000 IU d3 and 200mg magnesium at breakfast? what form magnesium is it?
if that is correct, then try taking another 200mg magnesium at bed time. and if you can handle it, another 200mg magnesium with lunch. if your mag supplement is magnesium oxide form, 600mg per day might send you running to the loo a bit often for your liking but if you have mag glycinate you should be able to tolerate 600mg/d.
you're taking some non-nutrients which is not my home turf, so, questions:
what are you taking hyaluronic acid for, is it related to the collagen, and is there a retinol or vit C connection? or manganese connection? i don't pay a lot of attention to manganese but studies have found it's low in the CSF of ms patients and i saw another study (guinea pigs) linking manganese status and low hyaluronic acid (also heparin actually...)
whatever your goal with HA and collagen, i'd say if you are worried about HA levels, that investigating your retinol, vit C, and mn status and correcting if low would likely kill more biochemical birds... but i don't know until i hear back more info about the reasons for this regimen
sorry about the pain. from what you've told me i think the d3 is sucking up all the magnesium and there's none left to make your other 300+ enzymatic reactions happen properly.
this high d3 same time as magnesium combo happened to me too, initially, and it reaaallly suuccckkkkeed. didn't affect my skin it got my throat but it can hit different folks in different ways. i thought i was going to die. it took two days taking magnesium at a different time for my throat to get better. kudos to one smart kitchener pharmacist. i went back later to make a point of thanking him.
my approach: no meds so far - just nutrient-dense anti-inflammatory whole foods, and supplements where needed
info: www.whfoods.com, www.nutritiondata.com