It depends on how much blood you are actually losing if you should wait a week or not. The weakness and pain/stiffness in your joints lead me to believe that you have an electrolyte imbalance going on. If you can, I would try to stay away from any food that is crunchy or really chewy (like jerky) and anything that is spicy. No raw fruits or vegetables. Stick with bland foods, like baked/mashed potatoes, rice, toast, cottage cheese and yogurt (if you can eat dairy), and clear liquids. I would recommend Pedialyte if you can stomach it, because it will replace some of the electrolytes that you're missing. I hear it doesn't taste very good. But Gatorade isn't actually very good for you if you're having diarrhea because it does have a lot of sugar which can make diarrhea worse. Also, Pediasure or Ensure will help with nutrition if you're having trouble eating, but because of the high nutrient content, they upset my stomach, so I would start slow with them. I make my dad milk shakes daily with an Ensure, vanilla ice cream, and canned apple pie filling that he really enjoys. He had UC and had his colon removed nearly 20 years ago, and has recently had jaw surgery so now he cannot chew. His nutrition is lacking, obviously, but this has helped him to put weight back on.
If you become too weak or fatigued, then this is a sign that you've lost too much blood and need to seek help immediately. But having 3-4 bloody bowel movements a day is probably safe until your appointment, unless again, you're losing a lot of blood in each BM. And sometimes a little blood can make the water look red, because it isn't supposed to be there at all and it's scary. Also, another note, pay attention to what you're eating/drinking. Some dyes are not digested when you are having diarrhea, and this can alter the color of you're stool. But you sound pretty sure that it's blood. (Probably TMI, but if I drink Koolaid, whatever color the Koolaid is, my stool is that color. And I would not recommend Koolaid with diarrhea, lol.)
I hope I've answered your question. I'll give you a couple tips straight from my doctor, that I cannot vouch for because I have not tried them, but she said they've worked for a lot of people. 1.) Bananas, peanut butter, and Fluff brand marshmallow cream on white bread. Make sandwiches. Supposed to be great for diarrhea and easy to digest. I don't eat peanut butter, haven't tried it.
2.) Apparently the World Health Organization released a recipe for decaffeinated tea that they use in Africa to help children to dysentery. 1 liter water, 1 tsp. salt, 8 tsp. sugar, and 5-6 decaf tea bags. She recommended lemon flavored, to cut the salt. I tried cranberry apple and it was disgusting. Couldn't drink it. The salt is supposed to help your body draw in the water in your digestive tract to relieve diarrhea symptoms.
Again, hope this helps. If you have any more questions, let me know and I'll try to remember to check the board again soon. Good luck and best wishes!