Continuing from part 3 (with the story starting at part 1):
我们到了医务室,这家楼看起来像实验室,而并不是像普通的医院。我看着我爸,他似乎已经对这个地方很熟悉,甚至知道怎么走。他说了“我的朋友在这儿工作”。我们一进去就看到医生了,而他带我们去他的办公室。医生立刻从桌子的抽屉中取出了一只注射器,说“这会解决你的体重问题 ”。我有奇怪的感觉,但是我爸悄悄地说“我已经告诉了他你来这儿的原因”。虽然我当时还有所怀疑,但我就只是相信父母而已,因此我让他给我注射。没有发现了立即而明显的后果,所以然后医生就走了,而我们回家了。
Please critique my writing. New words for me are in links. I'm at an "almost mastered HSK4" level.
I'm afraid 一进去就[...] is too often used in relation to premature ejaculation (一进去就射了), which would be totally inappropriate here. But maybe what I've written is okay.
Also I'm not sure if 而已 is appropriate.
I won't include an English version: that's not the point of this exercise. I'm fairly confident it's understandable (or at least if it needs modifying, it won't require much back-and-forth in the comments).