Please help! Mystery illness/unexplained symptoms RUINING MY LIFE. SO scared

[maddiesmummy1]

1. i can’t sit!! Specifically sit up for more than 10 minutes. Feel extremely unwell when sitting/sitting up. Only able to sit if feet up/under me and leaning back/chair has back. Feet also turn like reddish purple and like swollen when I have them down sitting down. Im very luck to work from home and able to lie in bed or feet up leaning back with back support working. A few nurses years ago and one recently commented that my heart rate is high when I sit up. Not sit, but when sit up.
2. feel very unwell after eating. Cannot stand at all, can’t sit, and need to lie down. For hours confused, dizzy, faint, lightheaded, sometimes chest pain. Feel heart race. Even after small protein snack like one boiled egg. What’s weird is This is relieved by drinking 2-4 strong cups of coffee with every meal or snack. But this is not postpandrial hypotension. A few times when measuring my hr standing up after eating I noticed it would be very high. Up to 160 bpm
3. Often feel physically weak. Difficulty lifting something light, bending down etc
4. there were a few months when walking I would feel like I’m being pulled into ground with great force, like gravity was 10000 times stronger. Body felt super heavy and pulled down into ground. Went away as soon as I sat down. This now went away but im worried it might return.
5. dont know if its related but a few people commented that my face sometimes turns like red/flushing

im 28.
gp run some blood tests which are fine, he doesn’t know what this can be.

please help I’m very depressed and scared. What can this be

It acts differently in different parts of the body. In the brain it’s a vasoconstrictor. Elsewhere in the body it can have a transient vasoconstrictor effect but then (and mainly overall) has a vasodilatory effect.

What is your diet and fitness like @maddiesmummy1
Do you exercise?

Put your symptoms into chat. It will tell you what to ask your GP at your next appointment. It's really useful in cases like this.

you need a cardiology referral. The pooling in your feet and the purple/red discolouration suggests a problem with venous return to the heart, so as @minipie suggested it could be either a heart pump issue or a compromise in a vessel. When the heart is stressed and can't pump forcefully enough, sometimes heart rate increases to compensate, so you need an echo, possibly an angiogram. I wouldn't waste time on anything else.

sorry if this is completely going down a wrong path but reading your description I was reminded of a youtuber I've watched for their wild camping (wildbeare is name of channel) who got a lot of strange issues with pain, exhaustion and POTs type symptoms. Turned out she had a sunken chest cavity (pectus excavatum) pressing on the heart that only started to trouble her in adulthood even though you'd have expected to be able to see it in childhood and more normally it would come in adolescence. You apparently are also at higher risk from this with a high Beighton score. She had a CT scan eventually and it was seen that the sternum was pressing on the right heart ventricle.

Apparently pressure on the right ventricle can cause narrow pulse pressure (tech term for blood pressure when the top and bottom numbers are close together) and high heart rate.

How long have your periods and your stomach been like this?