Sleep Regression

Has anyone else had a major sleep regression with their 2 year olds? My wee boy has been an excellent sleeper for over a year, but in the past two weeks things have totally changed. We used to be able to just put him down for naps/bed time and he would go to sleep on his own in minutes and would sleep until around 8 in the morning. Now when we put him to bed he keeps trying to come downstairs. On top of that he keeps waking between 5/6 in the morning and will refuse to go back to bed. I’m at my wits end as I also have a 9 month old who still sometimes wakes in the night so I feel like I’m barely getting any sleep.

Any advice please?