Novice rower hamstring problems

Hi, figured here might be a good place to ask for some advice on a training issue I've been having. For context I'm a novice male rower, I've been training as part of a club for about 3 months.

About a month ago I started doing 10k steady states during time off - 3 a week. Early on I noticed a change in how I was feeling on the erg. I was getting significant discomfort in my hamstrings, especially at the top. It wasn't stopping me rowing, but the pieces were feeling harder than steady state felt in the past and my average split kept getting slower. I figured perhaps I'd been over training a bit and a break might resolve things.

Despite not rowing for a fortnight, the problem has gotten worse. I tried a 10k this evening and couldn't even finish. I got to 7k and stopped as my hamstrings had been feeling steadily worse throughout and my lower back was starting to ache too. My split had slowed to around 2:25-2:30 by the end.

I'm just concerned that I feel very different on the rowing machine to how I have done in the past. I know that about 6 weeks ago I was comfortably doing 2x20min steady state at an average split of 2:12 and that felt tiring but good. Even early into these 10k pieces it's feeling pretty rough, in some ways even more so than in my 20 min test I did before starting my 10k pieces. Despite that, I don't even feel like I'm getting a proper workout, my upper body feels like it's not doing any work and I'm not feeling that much cardio stress either. It's all in the hamstrings.

Does this sound familiar to anyone? Could it be that my technique is causing problems? I know I must be doing something wrong but I'm pretty clueless. Any advice for getting past these issues would be really helpful.