lately for the past few weeks my right knee has felt like giving out, like when I am crossing the street and it hurts especially when I bend it. Should I see a doctor about this? This isn't normal for me. I've also gained a bit of weight in the last year and people are saying it;s probably just my weight. should I see a doctor?
I've experienced similar pains on my knees, they come and go (very rarely now) and are very sharp. I'm a hard-training runner (I'm currently on the track team of my uni), have been since I was 14 y.o. So, when I came with this to my doctor, he explained to me is because of the hard-core training I do. He advised me to slow down and beware of the effects this could have on me eventually but I'm a bit too competitive for that.
The reason of why you're experiencing this has to be completely different from mine. It varies, apart from the fact that we're all individuals, in age, nutrition, activity level and genetics. Weight is something our bones are used to carrying, and like you said you've gained just a bit (nothing drastic that puts you in the line of obesity, even then) there's no possible way this weight gain could be affecting your knees. See your doctor.
Peace.