Delayed cumming leading to going soft again

2 months ago i couldn’t stay hard and cum with a condom on during sex, could finish and stay hard with bj, hand etc. started using lube inside the condom and was able to cum and stay hard I was so happy… it worked for about 2 months and now the last two times I’ve had sex I’m not able to cum and after a while go soft again as a result which I think is panicking about not being able to cum, I’ve changed nothing and I’m very confused. Any tips?