Research is non-linear process. Keep an open mind and explore.
Tips:
Refining your research question to one that is well-focused and specific is the key to reducing frustration and stress.
Tip: In the discussion section of many research articles, the author proposes further areas of inquiry.
Tip: When you're searching topics in PubMed and find a promising article, try clicking the "related articles" link to the right of the citation.