7 week sleep change

My son is 7 weeks old (formula fed) and it seems like his sleep patterns have changed completely. From the beginning he was sleeping 2-3 hour stretches. Then, we would get one 4-5 hour stretch and then a few 2-3 hours. Last week, he slept 7-8 hour stretches and then a rocky rest of the morning (but who cares at that point). However, it only lasted 3 nights. Now, it’s worse than when we he was first born. We’re getting a 3-4 hour first stretch and then he’s up literally every 45 min to an hour. Whyyyyyy!!!??? How is this possible lol. He is on somewhat of a schedule, eats 5 oz every 4 hours during the day and then 3 oz at night, as he needs (usually only once or twice). We swaddle, noise machine, bath time routine before bed, all that good stuff and it seemed it was all working somewhat well until now. Is this normal? Will it go back??