nausea and a small lump on my stomach?

Good day I am 18 years old and I have been experiencing some strange symptoms my first symptom would be nausea and a small lump on my stomach, I also had a very short 3 day period I bled very little for two days hardly a pad full and on the third and fourth day experienced brown discharge only .I had a cold recently so I don't if that could be the cause I do however have a change of mood and I also been having alittle cramping but nothing hectic or painful . Are these symptoms pregnancy or are there other causes??