Side effects from juicing?

I got a juicer for a Christmas and started using it. I make fresh juice with veggies and some fruit and ginger. I’m not fasting or doing a strict juicing diet, just replacing breakfast with a glass of homemade juice.

But ever since I’m experiencing a lot of back pain and very very sore muscles in my shoulders and neck.

Could this be a side effect of the juice cleansing some of the toxins? Will it pass quickly? It’s horrible 😕