Re: Knee health and Aikido
I don't know how old you are or what your previous athletic history has been, however, every symptom you describe is a symptom of a meniscus tear. I have had all these symptoms and after slogging through the medical system and useless quad strengthening exercises, finally got someone to give me an mri and low and behold, there was a tear. Looking at arthroscopic surgery and about a three week recovery.
Bottom line is if it is bothersome and/or painful, get an MRI. Read by a competent radiologist, pictures won't lie.