Hi all, first time posting, hope I'm not doing anything wrong.

I'm trying to make a 3d Sketch for a welded frame I'm designing, and no matter what I do I seem to keep running into weird situations where Solidworks thinks the sketch is overdefined for reasons I can't even begin to imagine. I'll have a perfectly fine sketch, and then I try to draw a line connecting two points, or a circle concentric with another circle, and all of a sudden over half the relations in the sketch turn yellow or red even though I see little or no way in which the added element could possibly conflict with anything. Sometimes it even happens after deleting a sketch element, whereas before adding or deleting it the sketch seemed fine. I can't see how getting rid of elements can ADD to the defined constraints in the sketch.

Attached is the sketch I'm working on. For an example, in the current version (which, by the by, is one of about 5 iterations I've gone through trying various approaches, so forgive me if the sketch construction seems weird, I've tried going circles then lines, lines then circles, etc.) if I go into the top plane and try to add a circle about the origin, errors pop up. Why on earth can't the sketch accomodate a circle about the origin? What is this conflicting with? Any advice on how to go about making this sketch efficiently? The end design is supposed to look something like a birdcage with weldments accross each circular "stage" as floor frames. These kinds of weird conflicts have been popping up in seemingly random places as I've tried to draw this thing, sometimes while drawing the vertical beams on the sides, sometimes while drawing in the "floor" stages (which aren't included in the attachment because that's where the error pops up this time).

I really appreciate any help, thanks.