I was in second grade and my elo dropped from 1300 to 1000 in 2 weeks, I know how you feel. Anyway, you'll bounce back. Just be patient.
extreme elo drop

Around a year ago my elo was around the 1500's. Ever since this summer, I rapidly dropped to the mid-1200's. I am really worried, what should I do?
Play some games against Computer1-EASY. That's how I got my rating to 1700.

If your elo drops below 1300, you should go to a doctor.
Only if it stays below 1300 for more than 4 hours.

Be sure to seek medical help if your ELO drop lasts more than four hours
Well, for the OP it's already lasted at least 2 months.
The most likely answer is you weren't really 1500. For example if you played 1 person 10 or 20 times in a row, winning most (or all) games, it would artificially boost your rating.
If you maintained a 1500 for, lets say a month, and during this month:
1) You played rated games every day
2) You played a variety of opponents
Then the drop to 1200 is very odd, and likely only temporary.

If your rating falls more than 500 points, take a break from chess

It's more mental than it is your skill level. You're just going on tilt. You might find that once you hit rock bottom you will start to turn things around with a win or two then get a string of wins, and really boost your confidence. It can be really tough.

Sometimes is just you playing too many skilled opponents. For example i hit 2020~ blitz, but then next day dropped below 1900. While indeed i lost some winning positions vs lower rated at that time, but i found out most of my opponents were underrated. For example:
i am playing someone rated 1940. I check his profile - 2 months ago he was 2170 or simular with max win vs some 2250 and with avr rating of opponents ~2000.So i didn't lose to some 1900, but to 2100 rated player. Playing a lot of games vs same opponents can high sky your rating or sunk it so it's very inaccurate.
Also keep in mind that 1300 rated player with 1000-2000 games is way weaker than same rated but with 10 000-20 000 games.
Around a year ago my elo was around the 1500's. Ever since this summer, I rapidly dropped to the mid-1200's. I am really worried, what should I do?