Very similar experience for me too. 6 months absolutely fine on Utrogestan and gel. Pharmacy gave me Gepretix with no warning ... googled it and it looked the same. After a week I started spotting, menstrual symptoms and a full period (I even got a bit of acne). I contacted the GP and I've been given a new prescription for Utrogestan and told to discuss with GP at my appointment next month.
Very odd that this has happened as it's 'supposed' to be the same, but this was the only thing that had changed for me. I only saw the posts here after I'd contacted the GP, and I'll be sure to mention wider issues when I see her next.