Has my body built up an intolerance for coffee?

No intolerance build up that I know of. Think of all the folks that drink multiple cups a day for the better part of their lives (54% of US adults drink coffee everyday)

You can build tolerance to the caffeine over time, and have withdrawals if you don’t get the caffeine at your regular schedule, but that doesn’t sound like what you’re asking.

Your “freak out” was because caffeine is a stimulant for your nervous system. So your brain can’t relax with too much caffeine, but the threshold for a permanent effect would be really high.

I’d guess you’re just overthinking it. If you want to have some coffee, have some, but leave the 800mg binge alone. Beyond a bit to “wake up”, more isn’t better when you’re talking about stimulating your brain and heart.

Put another way, if you’re used to having a drink or two with dinner, then one day “jolt” your system with 7–8 shots in a short time, the feeling is going to be different.

More from wikipedia – Health effects of caffeine

Let me see if I have this straight. You had had your morning coffee, and then in the afternoon you drank two cups when you typically don’t and felt over stimulated and freaked out. Is that right? All that means to me is you crossed your tipping point. You took much more of the drug than usual, why is it surprising it affected you?

Is your regular morning coffee bothering you? You can also switch to a different caffeinated drink like tea or coke to see if it is just coffee causing the problem. I doubt it is the coffee, I think it is just the caffeine itself.

Now that I have quit caffeine, when I do cheat I am much more sensitive to the caffeine. I love it still, but only need a mini amount to feel great. Great until I withdraw and then I feel like shit, and look terrible also.

If you do quit caffeine, make sure to wean down for at least a few days, and expect headaches (take some ibuprofen or tylenol, whatever you usually take) for a couple days. You will be sleepy for at least a few days also. Honestly, it took almost a month for me when I quit to not crave it. I still really want it sometimes. I am really glad I quit though.

You have to treat caffeine like a serious drug and take it consistently or you suffer the consequences. If you miss your morning coffee you will have a headache, if you double your intake you will be overstimulated. It’s a very potent addictive drug.

I would say you just caused a higher level of caffeine in your system than you were used to. Have you stopped drinking coffee, or do you still drink it and worry about it? Sorry, but saying you can’t enjoy it anymore is a little ambiguous:-) If you stopped drinking it and miss it, try getting a small coffee, and only drink a little of it, and slowly. Chances are good that it was a one time thing. Or, if you’re wondering about coffee specifically, not just caffeine, have some decaf.
@JLeslie I’m the same way; used to drink a lot of coffee, then stopped completely for awhile. So at the holidays when everything was busy, I drank coffee and enjoyed all the extra energy! I like to wean off it by switching to tea, which has less caffeine, so as to escape the headaches. What I never expected by giving it up though, is that I feel better than I ever did while I was drinking it.

@JLeslie Yea I wasn’t feeling the effects of caffeine earlier that day. I was still sleepy when the lunch rush came so I jolted up on two cups of coffee in a row within 2 minutes.

Now I’m not comfortable with it at all. I won’t even touch tea, only decaf

Well, if you want to enjoy coffee, try decaf:-)

I never was a coffee drinker, my vice is Coca-Cola. I like tea as well, but the real fix trick is the Coke. I do eat more chocolate now that I quit caffeine, which I swear is the body knowing where it can get every little bit of the drug.