It is irresponsible to offer suggestions to solve this without putting my hands on the bike.
You say that it occurs when you are in 1st gear. Is that 1st gear on the wheel AND at the crank?
What sort of sound are you talking about?
Does it happen while you are pedalling only?
Have you crashed the bike onto the right side of the bike?
What is the condition of the chain? Rusted or kinked, or any stiff links?
Why would the sound stop if you shook the bike?
There are so many questions that need to be answered. Offering a solution such as adjusting the limit screws is jumping to conclusions without doing the proper investigation. I would never tell a client that I know exactly what the problem is without having put my hands on the bike first. [http://mikefixmybike.weebly.com/bicycle-repairs.html|A good mechanic] does exactly that. Asks relevant questions and does proper investigating to solve problems.