HondaCivicForum.com - 1996 Honda Civic DX overheating

Hi everyone. So here's the situation - my 1996 Honda Civic DX is overheating. Here's a little timeline of what's been happening and what I've done -

- About 3-4 weeks ago, I noticed my temp gauge was a little above the middle which was never the case before. Since that time, I've been driving the car a ton for work, etc.
- About 1-2 weeks ago, I noticed when my car was running at idle, or I was in heavy traffic, at a stop sign, etc.. that the temp gauge started going up about 3/4 of the way. Once I hit the open highway though, it seemed to go down. So, I just figured it was a fan issue or something because the wind from driving at high speeds seemed to cool the car down back to the middle of the temp gauge.
- About a week ago, I noticed it was running about 3/4ths up on the temp gauge more consistently, so I put coolant in there and it helped temporarily.
- About 4 days ago, the gauge went all the way up while I was in traffic. I turned my car off while I wasn't moving, or at a stop sign, in hopes to prevent any extreme damage happening.
- About 2 days ago, the temperature gauge went all the way up while driving on the highway, so I immediately stopped at a gas station and filled it up with more coolant. I also put more oil in the car. Then luckily, the temp gauge went back to normal for the rest of the 25 miles I had to drive, and the 25 miles I had to drive back to where I was later that night.
- Yesterday, I was driving home from the location I was at, and again.. the temp gauge went all the way up and there was nothing I could do about it other than stop, park, and turn the car off to prevent damage.
Luckily I made it home with my car somehow and it still running normal (minus the overheating that the temp gauge indicated).

So... today I checked for white smoke. Didn't see any. Checked the colors of the oil and the coolant.. both looked totally normal. Checked the fan by the radiator.. it kicked on so the fan does work. Checked for leaks.. didn't see any. Then I did some research online, which led me to putting in a new thermostat. Did that, and still.. the car fully overheats. My Dad mentioned to try turning on the heater.. and apparently the heat doesn't work either since this has been happening. Also, when I did change the thermostat and let the coolant drain out before replacing the thermostat.. I noticed that what drained out of there.. looked like its normal green coolant color.. but had some black particles in it.

If anyone knows what is wrong, what I need to do, etc. It would be greatly appreciated! The car is still running fine and nothing has exploded or started smoking.. and I do not plan on driving it until I know what this issue is because I don't want to ruin my car.. unless its already ruined? Let me know what ya think, thanks!