I got this tree about 4 months ago. First couple of months it was fine. Then I noticed some spider webs on it so I treated it a few times with neem oil. The spiders seem to be gone but now (past month or so) the leaves have started browning at the edges and dropping. The brown parts are dry and some places cracking.

As far as care... I've been doing whatever they said to do. Watering it every week or week and a half, whenever the top inch of the soil is dry. Keeping it near a window but away from direct light and any drafts.

Can someone take a look at let me know what I'm doing wrong? Here are a couple of more pictures