Pain in biceps during extension with dumbbell

I've recently started trying to build up a bit of muscle cause though I've always lead a very active lifestyle it's been mostly cardio that I've invested myself in and I'm not quite happy with my body.

An issue has arisen which I mention on the thread title: the minute I started my weight training I noticed some discomfort in the lower part of my left biceps, close to the joint.

I can do the flexion part no bother but when I extend and straighten my arm, as I lower it, I feel this discomfort in the area I mentioned. It feels as if something kind of stuck for a second, then when the arm is completely straightened it's fine.

It got worse at some point a few days ago and I couldn't even do a push up, I felt the pain in the whole joint area around the elbow so I stopped working out till it was better and push ups were no longer painful. Yesterday I decided to resume the weights (biceps flexion and extension) since my arm was fine with push ups, but the same discomfort started upon extension, then I did some shoulder abductions (also with dumbbells) and it became painful again around the whole elbow joint area, it almost felt as if the joint was gonna break.

I want to believe it may be lack of training and that I just need to get used to the weights but I'd like to read some advice of anyone having experienced similar issues.

Thanks in advance for any replies.