How do I get rid of a sour smell from my bed?

It sounds like something textile has gotten wet and then dried too slowly.  It's quite a hard smell to kill, even after cleaning up the cause.  How are the laundry arrangements?  Is everything getting dry enough?  Sometimes you can mistake warm for dry when getting things out of the drier.  I had a flatmate who constantly smelt sour and I know it was because she was too impatient with drying her laundry.  She used to hand me my own laundry still damp because she thought it was excessive in my drying.  For you though, whatever the change causing this, this must be recent because she was totally nose-blind to it.  How is the room and the placement of the bed in it?  Is the room very cool so that it draws condensation from warmer parts of the house?  Does it get aired enough?  Is the bed against an outside wall?  Can air circulate freely around the bed including beneath it?  (I got mildew when I put underbed storage boxes under the bed because the floor is cool and there wasn't enough air flow.  It was quite a shock!)  Do you air the bed before making it up in the morning?  If you happen to sweat a lot this can be a cause, though even average people sweat a lot more in their sleep than they want to know about.

Is there anywhere else you can sleep for a few days?  General disinfectant spray isn't going to cut it.  You need a mattress cleaning spray that neutralizes the cause.  It usually takes more than one application and it will look worse before it looks better.  Then I'd dry it out on its edge for several days in a heated room and run a dehumidifier during that time if I could borrow one.  Then I'd give it a good spray of  odor neutralizer and be very sure that the mattress is dry before laying flat again.  If you use a comforter or quilt those can also be slow-drying culprits, as can your pillows.  For pillows use sweat-proofed protectors under the pillowcase and resist any temptation to read in bed with wet hair.

Make sure you air your bedding before making your bed and be old-fashioned and open the window every morning while you have breakfast, then go close it and make the bed afterwards.

Did you spill any kind of dairy product? Take the mattress off the bed. Make sure nothing is underneath.

The easiest way nowadays is to somehow contract a dose of good old Covid which, apparently, disrupts your sense of smell. Good luck.

Look underneath mattress for a lump of Limburger cheese.