Yellowing is caused by many things. If it is just on one branch, it could be root rot or insects such as spider mites. Flowering could have been a last ditch effort to survive by setting seed, and the yellowing related because the roots are too wet, too dry, or the soil is exhausted.
So, check moisture and be sure pot drains well.
If it hasn’t been repotted in 2-3 years, repot with fresh potting soil.
Check if roots are white to cream in color, not black and mushy.
If any sprays were used near by, leaves could be reacting to the spray used.
The occasional exposure to full sun can sunburn leaves that are not accustomed to full sun. On sunny days move the plant back or put a sheer curtain or cloth between the window and the plant.
If all these issues don’t seem to be the case, consider sending pictures and some sample branches showing the problem, but still having some green, to MSU Plant Diagnostic lab. They can diagnose the problems found on the leaves or branch and suggest remedies-
Here is a reference on the most common insects and how to handle them-
This reference has some advice on potting soil, drainage, pests, and general care, should you need it-
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