Red feet

I got a problem to my feet. I went to hospital several times, but no doctor was able to give an explanation.
This is what happened:

I have never had problems to my feet all my life. And never had any operation.
One day, when I woke up I had some pain in my right feet, between the third and the fourth metatarsal. I thought it was nothing, but the pain increased during the day. The late afternoon I could not even walk because of the strong pain and my foot was red and swollen.
The day after the pain was down but the whole area was still swollen.
I went to hospital. The doctor checked if the bones were broken. But from the radiography my bones looked ok.
The doctor suggested a blood check. He gave me some drugs for pain.
In few days also my left foot had the same problem.

The blood analysis showed some possible bacteria in the blood, but nothing else that could explain my problems.
The doctor gave me some antibiotics and more drugs for pain.
After one week my feet were not much swollen anymore, only in the evening they were still becoming a bit swollen. But touching my feet, I could feel they were not ok, especially in the area where everything started ( between the third and the fourth metatarsal ).
It was not a continuous pain. It was like after a hit, when our skin becomes yellow-blue and it is a bit painful at the touch. Plus a particular was that taking shower and putting hot water on the feet, they were becoming red, much more than the rest of the body.

I went to hospital again. I got new blood check. The result of the second blood check showed no more bacterial connections.

The situation of my feet didn't change. So I went to check if it was anything about the blood circulation. The doctor checked, but he said that everything was ok.

Some months passed now and I'm still not fine.
No more strong pain like in the beginning, but my feet continues to become red in the evening or under warm water ( the red color starts from the ankle and goes till the fingers ) and to have some pain at a normal touch.

What could it be?