My whole life I have had this problem where if I stand for too long my legs start to get hot, itchy, and red splotches appear and it gets worse if I go through temperature changes, especially heat. Every doctor I've asked about this has been at a total loss and the only suggestion I've had is heat rash (although it doesn't look like heat rash, more like blood pooling). For a while I just ignored it, but recently it has been getting worse. It's happening within minutes of me standing and it's going further up my legs and to my butt. I've also started to get the red splotches on other parts of my body like my chest, shoulders, arms and face (although they don't hurt or itch as much as they do on my legs). Sometimes my face just gets randomly flush, but I don't feel hot at all. It's really started to affect my quality of life and I'm scared it's just going to get worse and worse if the issue goes unchecked.
All that being said, I don't have any other allergies that I'm aware of. I don't even get bad seasonal allergies most years. I do experience some gastro intestinal symptoms, but nothing that couldn't be attributed to other conditions. I have never had any respiratory issues. As far as I am aware this is the only major symptom I have like this. I have a connective tissue disorder (loeys Dietz Syndrome), but it's rare enough that there's not much research about a connection with MCAS (it is very similar to EDS though)
So is it possible that this is MCAS or is there something else that could explain this? What would I need to do to get concrete answers on this?