Concerned about baby’s sleep (or lack thereof)

Our 6 month old has really never been too good of a sleeper and we are concerned there’s something going on with him. My husband is really concerned that he had nervous system issues. Baby has never taken good naps, literally only sleeps 30 min on the dot and will only sleep longer if we come in and rock him to a relaxed state again, then sometimes he’ll sleep over an hour. Usually he sleeps 2 hours total throughout the daytime. Yesterday he slept less than an hour total. At night, he wakes up frequently, every few hours. Last night he woke up many times, with the longest stretch being 2 hours. I love him and I’m worried about him and it’s very hard on us to be waking up so many times. Sometimes he’ll sleep long stretches and we will get sleep, the maximum stretch he slept was 8 hours one time which was great. But most nights he wakes up 1-2 times at least. I supplement so I’m trying to feed him as much as possible so he’s getting his caloric intake and I make sure to offer naps around every 2 hours and I also make sure he’s getting lots of tummy time. I’ve also been trying nap training and he was doing so well but I feel he’s regressed and needs extra help falling asleep now. His sleep quality ebbs and flows literally every couple of days from good to bad so we never know what to expect. For some reason we all haven’t been able to sleep usually before 11pm but we try every night to go to bed earlier. My husband has to wake up at 4:30am every morning so it’s killer. I made him miss work today because he wasn’t getting any sleep and I’m so worried for his health