Leg Day Issues

I've been having an issue every time I do leg day at the gym. As I'm exercising, I start feeling extremely tired. Just today, I got a pounding headache and extremely dizzy in the middle of a set. When I finished the set, my eyes started to strain from the light. I checked my pulse and it measured at roughly 180 BPM. When I was driving back, I coughed and I felt pain spike down my legs.

I have very strong legs due to my genetics, being able to push 800 lbs on the leg press just a few months into my weightlifting journey. The main issue was my balance. I could hardly do 135 lbs on the squat rack without losing my balance and having to bail. I'm a senior in high school, and I just turned 18 a few months ago. I'm afraid that I'm permanently injuring myself and I don't even know it.

My usual leg day is as follows:

3 sets on the squat rack

2 sets of leg extensions

3 sets of hip thrusts

2 sets of hamstring curls

2 sets of hip abductors

2 sets of hip adductors

3 sets of calf raises

All of these are separated by 2-4 minute rests, depending on how out of breath I am. I've been going to the gym since I was a sophomore, and I'm not on any kind of steroids. I don't make enough money to buy them anyways. Does anyone know why this is happening, or any potential fixes?

It sounds like your blood pressure is getting elevated to a high level. You may need to reduce your volume a bit and build back up slowly, it sounds like you're doing too much too fast.

yooooooooooooooooooooooooooooo

quick fix

(impressive set/routine you got btw)

look, having muscle mass and strength is great, easy to gain and maintain in your early years

but if its 

both the symptoms at the end and the lack of balance

my best guess is that 

1. you are shocking your leg muscles which could have some great potential risks/rewards
2. youre not getting enough cardio on your feet aka running, climbing, hiking, ect

remember, you have your main muscle groups everybody knows, loves, and yeah sometimes abuses/misuses

but you also have minor "subgroups", and other high value functional systems like tendons and ligaments

gotta incorporate it all baby

First, make sure you're eating enough, carbs as well. Carb give you more strength and less tiredness.

Although you can lift heavy weights, remember that your muscles can handle the weight, but it may injure your tendons and knees. If you still do leg press, lower the weight and increase fatigue by adding 2-3 more reps and a cadence 2020 or 2010. That way you can strengthen your tendons and avoid future injures. Tendons takes time to strengthen.

The dizziness you said I suppose that it may be breathing. Make sure you breathe correctly during the sets, avoiding blackouts and injures.

Your leg routine is nice, but I'd say if you're less than 2 years training, maybe you should lower the volume, split into 2 days (if you're doing legs 1 day per week). Focus one day more on the quads, the other day on hamstrings and glutes. More volume not always equals to more gains.

And, of course, you should always go to a doctor and describe these situation.

To echo Krastov, both the dizziness and extreme headaches sound like they could be breathing related.  It's pretty common under heavy exertion to hold your breath in while bracing your core (valsalva maneuver).  It can help you get that last rep, but it can also cause a pretty brutal headache, dizziness, or worse.  The effect can be especially bad if you already have high blood pressure as the valsalva maneuver can spike blood pressure.

I try to be conscious of breathing in on the negative/eccentric phase and exhale on the positive/concentric 

ur probably not hitting ur micros or not drinking enough water the day of and the day before your leg sesh.