How to deal with co-worker that has become lazy?

Hi all. 24f working in primary care, I got promoted a few months ago to run our medical assistant mini clinic (taking vitals, sugar checks, pre-op testing, injections etc), every appointment is 15 minutes and we go up to 45 for things like spirometry testing & such. Sometimes I get up to 20 people on the schedule including providers in the back who need something done on patients they’re currently seeing. Recently our clinic has hired an outside agency to come in and perform echocardiograms on our patients daily. The tech sees about 11-12 patients per day added on to my already kinda busy schedule.
I share the mini clinic with our office XRAY tech (55m) who was also hired on 4+ years ago with the understanding he would be doing MA duties. Which he has been with everyone who has had the job before me. Recently he has been forgetting a lot of things, like scanning meds into charts, finishing notes, not inputting vitals. Which I have to go back and correct. This morning three patients were here at once, he left the room to make a phone call. Leaving every one to me. Today he left a patient sitting in the waiting room for over 45, not even notifying the tech that she was ready.
I prep all the charts also, right now I’m prepped out until 8/27. 22-26 patients a day. He’s very nice and we’ve worked with each other for 2 years now. but I really don’t want to make it an issue when I tell my boss what has been going on. Is there a good way to go about this?