When faced with a big worry, it is natural to feel overwhelmed and stressed. Fortunately, there are several synonyms for this phrase that can be used to describe the same feeling. One alternative is "major concern," which implies that the issue is serious and requires attention. Another option is "grave worry," which suggests a deeper level of anxiety and fear. "Significant apprehension" also captures the sense of unease and nervousness that comes with a big worry. No matter which synonym is used, it is important to acknowledge and address the issue to avoid further stress and anxiety.