This is really common.
We are like sponges who through our daily lives pick up stress all the time and in heightened anxiety situations we feel like we are going to explode like a volcano errupting with tears, we well up.
This is great because it means we have the ability to release the stress. The problem is we dont want everyone to see us cry so this induces more stress. What do we do? - We learn to release the stress in our daily life in a controlled way. You will see some people release this stress on their loved ones or work colleagues it manifests in the form of shouting, crying, usually with anger or anxiety. We havent found how to use this valve of releasing stress and tension.
Some people exercise, others try karate, sports, yoga/meditation, others block this stress by drinking excessively or taking drugs.
Its why people generally feel alright once they've had a good cry.
Understand it isnt a bad thing, you may just want to find another alternative to releasing this stress.
Jack