What Causes Blood In Urine?

Question: Hello, this is XXXXXXX I have bled from during urination several times of late. I have many health problems, i.e. Avascular Necrosis throughout much of my body brought on by massive doses of Prednisone to treat Hypersensitivity Pneumonitis from 1998 to 2002. I was diagnosed with AVN in 2003 and MRI's revealed that it was in my left shoulder and both hips. In 2004 I had the Left hip replaced and 2005- the left shoulder. Last Sept. the right hip was replaced. In addition I've suffered from dbl. pneumonia four times, bring on a ventilator twice, 18 days the last time. I have a hospital bed in my home and am on oxygen 24/7. I suffered a mild stroke in the summer of 2015, no paralysis. In March I was rushed to ICU when my blood pressure nearly bottomed out. My point in saying all this is to point out that I have been Hospitalized a lot!
In the past 90-120 days I am urinating only 1-2 times a day, this comes and goes. The urination is very dark. In addition, I am on a tremendous amount of pain medication as the AVN has gone into my left femur, the knee is totally gone with AVN, Severe Arthritis and 2 Torn Meniscus and the Tibia and ankle is full of AVN, allowing no blood flow through these most important bones . The surgery will require operating on the entire left leg by replacing the entire kneecap, removing the femur & tibia to drill out the AVN, placing rods in both and cementing them back in, provided they don't break or crumble from the bones being over 2/3 dead each. Also, I was put on an anti-inflammatory 3 months ago. The source of the major pain at this time is in the lower right back, for which there is an exceptional amount of swelling, the back on into the top to mid hip area. Should I consult a Nephrologist? Should I try to see someone right away given these symptoms (excessive pain, swelling, location, bloody and very little output of urine some days and the incredible amount of medication I am on?) Please give me some medical reasoning i.e. possible kidney failure or calcification of the kidney? Sorry such a lengthy page and information, I just wanted to make sure I covered all my problems. I will require a new shoulder replacement at XXXXXXX Clinic, Heart Catheterization and a Right Knee replacement.