Shaw, who has been restricted to substitute appearances since his return to fitness, has suffered a setback.
Shaw has a new muscle injury and will be out for at least a few weeks, if not longer.
"It is hurting a lot having to write this as I really thought I had got through my recent struggles and was on a positive path going forward, but unfortunately I've had a small setback," Shaw wrote on social media.
"I've been through a lot and had a lot of ups and downs, but this has been my toughest period.
"I'm absolutely devastated and it's extremely tough to come to terms with reality at this time.
"I understand there's going to be people frustrated, angry, disappointed and I understand all that. There is no-one feeling that more than me at this moment in time."