Back pain while lying down. Tumor!

Hi I have left shoulder and neck pain on and off for 3 months. For the last 2 weeks my pain has increased in my upper back specially in my left shoulder blade and few areas along my spine. I can feel a crawling sensation on my back when I lie down and shoulder blade pain also increases while I lie down. Pain becomes better with moving and increases while sitting/lying down on my back though once I change my position to side ways while sleeping gets better. Online everything says pain while lying down is very serious. What could be the reason for this ... I did start a new work out but that was just 4 days back. My local doctor says it is a spasm , I am worried if it's a nerve issue or spinal tumor