Feeling like giving up..

I have been an LPN for 5 years. I've worked in two different provinces and have had much different scopes or practice in both. Currently, I'm at the lower end of my scope in Atlantic Canada and am treated like low class citizen by the "real" nurses. My confidence as a "nurse" has been depleted so much that now I question my work, my competency, my critical thinking.. The whole lot. I am over diligent and make mistakes and beat myself up for days after. Today I overlooked something and felt like a complete idiot. I took off new orders for a patient and it was at 1545. I put the order in the slot for it to be delivered to pharmacy without thinking they would be closed at 4. I felt so STUPID when I was questioned about it at 8pm when the staff coming on asked why the meds weren't there. I stated "same meds but different dose" so I thought it was fine, but it wasn't. I never thought that it would be a different tablet for new dosage changes. I was so anxious today that my critical thinking was literally in "off" mode. I was so concerned about being perfect and being the best u could be that I made myself look like an idiot. I float at the facility I'm working at and have been here for a year and feel so dumb because I still ask (what I think) are silly and you can tell staff are annoyed. I guess I'm just looking for guidance. Has anyone else had these feelings 5 years into their career? I felt so confident at my last job (3.5 years acute care medicine) and received compliments from patients, staff and family constantly. Here I receive nothing and am made to feel like a disposable and not important "LPN". I'm ready to give up. I feel like if I don't get it now, I never will. I care deeply about my patients but feel I'm too dumb.