I am working on streaming API and I got track limitation notice. I don’t know how to handle this issue.
This is normal, expected behaviour - you just need to adjust anything that relies on tweet counts to account for missing data: https://twittercommunity.com/t/rate-limit-in-streaming-api-what-does-the-track-number-mean/9560/2?u=igorbrigadir
And Shall I run streaming API and REST API simultaneously in the same account?
Yes, that’s fine - Streaming connections & REST endpoint connections are completely separate and don’t interfere with one another.