You need to provide full details on the experiment that you performed. What was the geometry of the diffraction experiment (Bragg-brentanto, Debye-Scherrer., wavelength, specific instrument and sample holder ...) If a Bragg-Brentano isntrument was used, how was the sample prepared, how thick is the sample. In Bragg-Brentano a common issue is to have a very small amount of powder on top of a support. if this powder is mounted too high, the flat incident beam will, experience a hefty amount of absorption at low 2-Theta angles. and the background will be too low. Finally, why is the pattern of such low counting quality. The intensities of all peaks are way too low for a proper analysis. Use much longer counting times!
You actually observe increase of your background after ~20 2theta and it is due to fluorescence if you used Cu radiation. This is also the reason why your peaks have low intensity. It is quite common to observe it when you analyze Fe containing samples with Cu radiation. You can either use secondary monochromator in order to cut the parasitic radiation coming from the Fe fluorescence or you can use different kind of x-ray radiation (in case with Fe containing samples Co x-ray tube is quite suitable).
In case you didn't use Cu radiation then you'll have to provide more information on the experiment like R. D. Neder and Omar M S already suggested.