Fast heart rate, weird breathing (and more). ER, urgent care, or simply rest?

19, ~340lbs, ~5'6" afab, i dont smoke or drink. I take multiple medications, ill list what i can remember: sertraline,omeprezole, metformin, bupropion,naltroxene, and one for adhd that starts with a c and is taken before sleep since it causes drowsieness but i cannot remember the name. I think its for adhd, thats at least why it was prescribed

Now i could entirely be overthinking this. Hence why im asking before i make any major decisions.

Since yesterday ive had a heightened heart rate, sitting, standing, laying down. Slight difficulty breathing (chest feels tight, breathing feels like a chore, but im not actively gasping though i have to remind myself to breath in full breaths). Occasional chest pain, though not deep in the chest, its more in the breast area and could be unrelated. (I dont have good support in my bra atm).

There is also the occasional pain at the bottom of the sternum area, almost forgot to include this till i stood and it came up again. Probally from the issues above but also extreme exhaustion, i slept the rest of the day after work yesterday and couldnt get out of bed for more than an hour without needing a nap. It gets worse with any sort of movement or change in breathing. (Walking to the kitchen, drinking water, eating, etc). Im also minorly disoriented/dizzy and have slight issues with my hand coordination occasionally.

This started when i pulled my back at work (fresh cut produce. I was lifting watermelons all day.) The muscles around my shoulder blade hurt, espesially when a deep breath was taken, though the pain subsided after a 3hr nap at home, but the exhaustion and difficulty breathing didnt go away. The heart rate comes and goes, but most of the time im able to feel it in my throat and im always constantly aware of it.

Googling wasnt much help, everything that came up described symptoms in a way that i couldnt tell if mine were severe enough to count as what they were describing and i dont want to waste everyones time going to an urgent care or ER if i dont have to. But i also dont want to not go and need to and then collapse at work tommorow or something.

I do plan to go to the doctor on monday, although idk if my work will be quite happy with me calling out for possibly multiple days in a row just for that wait. (I work saturday and wont know until then when i work next. Or if i go in today to check)