Why does sweat stain my white t-shirts pink?

Question:When I have a hard jog I sweat a lot. My white t-shirt is soaked. When I take it out of the linen basket 3 days later to wash it, it is covered all over in bright pink blotches!
Things that may be relevant:
This doesn't always happen.
The pink washes out with a bio-soak and a hot wash.
I use non-bio liquitabs and an easy-iron conditioner.
I use a 'no-white marks' deodorant spray, but the pink marks bear no relation to where it is sprayed, and as I jog in the morning, there would only be old deodorant still on my body.
I take aciclovir for an eye condition; cetirizine for hay fever; salbutamol and beclomethasone for asthma.
I often drink white wine the night before so there is probably alcohol in my sweat.
I often eat spicy foods. The night before the last time, I ate spaghetti bolognese with some added chilli.
This has only been happening since I bought a new simple reed linen basket with a full white linen lining. The t-shirt doesn't touch the basket, or anything red or pink

Answers:
I thought this was an interesting question because my husband had a couple of t-shirts that the same thing happened to. I have no idea what caused it. He also takes allergy medicine, drinks a few beers, and eats spicy food. But of all his jillion t-shirts, it only happened to these two. I have no idea what caused it, but it must be something about the material since his other t-shirts are not affected.