Can stress cause you to forget things? lose your train of thought while speaking? this happens several times a day...

Yes: Yes, stress, anxiety, depression are very common causes of memory loss.

Yes, in some ways: Stress affects some types of memory, depending on the cause and severity. One way chronic stress may negatively affect your recent memory is by disrupting your brain’s ability to attend; causing problems with information making it into your memory in the first place. Remote memory is much less affected by stress. Losing a train of thought happens when stress affects executive functioning, too.