From my experience & what I have read it can get worse before it gets better sometimes...& if you cave in on just one occasion, it can go back to square one & sometimes worse
I did notice you said your dh, was "checking" every 5mins, I assume that you are doing CC... from my experience with doing CC at 9mo, it took us way backwards & made separation anxiety worse... I think a much better option is to do Pick up /Put down, where you are there with your lo the whole time, then they are "trusting" you that you are helping them go to sleep, rather than CC, which leaves them to "sleep from exhaustion or despondency" & if they are aged 7-12months, can also make them feel abandoned & wake up more...which does sound like the case.