small,skinny,stressed and constipated is a classic vata disorder in ayurveda. if your stomach is bloated on top of this, it indicates extreme vata disturbance for which bone marrow is indicated.
i suggest a vata pacifying diet...
look it up on the net but a few things that will help are: egg yolks, mayonnaise, salt, oily foods, most spices, warm foods, avoiding dry foods, eating regular meals, sunlight, avoidance of cold temperatures and wind.
the herb asafoetida in particular is very good for pacifying vata. ginger is also good for dispelling excess gas.
fresh papaya can be good for eliminating the vata constipation.