What Can Be The Reason For The Eye Turning Red Suddenly?

About a month ago, I woke up and my left eye turned bright red on one half and it didn't go away. I wear contacts normally, but I hadn't slept with them in that night or anything out of the ordinary. I went to a family practice doctor who checked and said my cornea was unaffected but recommended I keep my contacts out for two weeks. I went o an optometrist later in the week who said I probably had a subconjunctival hemorrhage. After two weeks I went back to wearing contacts. Four or so days ago, I noticed my eye was starting to get very light sensitive. Now, it has gotten to the point where I have intense pains when I open it, but the pain comes in waves (I'll hurt for an hour and it'll turn bright red and water, then I'll be fine for three hours). I noticed that it looked like there might be some bruising (it looks lighter than bright red blood) around my iris. I've kept my contacts out for two days and it is still troubling me immensely. Any idea as to what might be going on?